[c10] Take advantage of c10::str optis for simple CAFFE_ENFORCE (#52223)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/52223
After the previous diffs, `c10::str()` will return a
`CompileTimeEmptyString` when passed 0 arguments and a `const char*` when
passed 1 `const char *` argument. We can take advantage of this to
outline further std::string creation from CAFFE_ENFORCE.
ghstack-source-id: 121877053
(Note: this ignores all push blocking failures!)
Test Plan:
Compare assembly for
```
#include <c10/util/Logging.h>
void f(bool b) {
CAFFE_ENFORCE(b);
}
void g(bool b) {
CAFFE_ENFORCE(b, "message");
}
void h(bool b) {
CAFFE_ENFORCE(b, "message", random());
}
```
before & after this diff.
before: P174902847
after: P174902912
f & g are clearly much improved, and h is about the same.
(I tried measuring caffe2 perf on the AdIndexer MergeNet benchmark, but didn't see a win, which makes sense because the change is small.)
Reviewed By: bhosmer
Differential Revision: D26405181
fbshipit-source-id: c51a9e459ae7d9876494a83ade6f6fe725619512
